A known two-wire type current output sensor is disclosed in JP10(1998)-332725A. The disclosed sensor includes two external connection terminals. One of the external connection terminals is defined as a power supply terminal to which the power supply current flows from the outside, and the other one of the external connection terminals is defined as a GND terminal (output terminal) from which the power supply current flows to the outside. In addition, the current flowing from the GND terminal (i.e. current level) is changed in accordance with a detection signal of a detecting element to be an output signal. Therefore, only two wires connected to the power supply terminal and the GND terminal are required for a supply line to the disclosed two-wire type current output sensor.
The aforementioned two-wire type current output sensor is mainly used as a rotation sensor for ABS, AT, and the like in the vehicle. The direction of flow of the current is decided at respective (i.e. two) external connection terminals. That is, as shown in FIG. 7, for example, two external connection terminals T1 and T2 are provided on a sensor body 10 on which a rotation detecting IC (current output IC) storing a magnetic detecting element S (Hall element) and a signal processing circuit 100 is mounted. Then, one terminal T1 is determined as the power supply terminal and connected to a power supply side terminal VIN of the rotation detecting IC while the other terminal T2 is determined as the GND terminal and connected to the current output side terminal OUT of the rotation detecting IC. Rs is a detection resistance provided at the outside.
Further, the aforementioned two-wire type current output sensor includes two magnetic detecting elements for outputting respective rotation detection signals having different phase relations from each other in accordance with a rotation direction of a rotating member (detected member) so that the rotation direction of the rotating member in addition to the rotation speed can be recognized. Then, the signal processing circuit changes the protocol of the current output signal in accordance with the change of the rotation direction of the rotating member (for example, the current wave is changed in accordance with the rotation direction).
According to the aforementioned current output sensor, the detecting element face (i.e. face of the sensor that can detect the detected member via the detecting element) is provided on a predetermined side of the sensor. In addition, two external connection terminals T1 and T2 are determined as the power supply terminal and the GND terminal respectively. Thus, the mounting arrangement of the signal processing circuit 100 (precisely, the rotation detecting IC and the like) is restricted such that the power supply side VIN of the rotation detecting IC is arranged close to the power supply terminal T1 while the current output side OUTS of the rotation detecting IC is arranged close to the GND terminal T2 as shown in FIG. 7. At this time, if the power supply terminal and the GND terminal are switchable when designated for the respective two external connection terminals, i.e. the power supply terminal T1 may be determined as the power supply terminal while the power supply terminal T2 may be determined as the GND terminal, or the power supply terminal T1 may be determined as the GND terminal while the power supply terminal T2 may be determined as the power supply terminal regardless of the mounting position of the signal processing circuit 100 (precisely, the rotation detecting IC) on the sensor, the designing flexibility of the harness for supplying power to the sensor and the like may be increased.
Further, a left-wheel rotation sensor and a right-wheel rotation sensor for ABS, for example, having a function of detecting a rotation direction include sensor bodies 10A and 10B respectively being symmetrical each other. In addition, respective harnesses for power supply with respective connectors CNs having the equal terminal arrangement to each other are used for the left-wheel rotation sensor and the right wheel rotation sensor. The sensors should be configured such that respective rotation base directions for the right-wheel rotation sensor and the left-wheel rotation sensor are different from each other.
That is, since the detecting element face of the rotation detecting IC is determined to be positioned on one face (front side) of a package of the IC, a rotation detecting IC 1 for the left wheel and a rotation detecting IC 2 for the right wheel should be mounted on the sensor bodies 10A and 10B respectively such that the ICs 1 and 2 are symmetrical each other to thereby bring each detecting face (front side) faces a rotor L. As a result, in the left-wheel sensor, a protocol 1 is output in the rotation direction in which a magnetic pole of the rotor L is detected in order by detecting elements 1 and 2 while a protocol 2 is output in the reverse rotation direction. At the same time, in the right-wheel sensor, the protocol 1 is output in the rotation direction in which the magnetic pole of the rotor L is detected in order by the detecting elements 2 and 1 while the protocol 2 is output in the reverse rotation direction. Accordingly, two types of signal processing circuits or signal processing ICs are required so that the rotation base directions for the left-wheel sensor and the right-wheel sensor are different from each other, which may cause a cost increase.
Thus, a need exists for a two-wire type current output sensor and IC therefor whose two external connection terminals can be switchable between a power supply terminal and a GND terminal.
In addition, a need exists for the two-wire type current output sensor and IC therefor that can reduce a mounting restriction by using an IC package storing a detecting element without decreasing the detection performance.
Further, a need exists for the two-wire type current output sensor and IC therefor that can employ a single type of rotation detecting IC with a function of detecting a rotation direction of a detected member for rotation sensors having symmetrical sensor bodies each other.